There is a need in many industries to economically recover valuable products from what are considered to be wastes having a high moisture content and a non-uniform particle size. It is desirable to recover valuable products with greatly reduced moisture content, substantially uniform size, and without significant loss of beneficial attributes of the material. These industries include the agricultural, food processing, mining, coal, pulp and paper, and oil and gas industries. As one example, in livestock feed lots raw manure is produced in large volumes, and the most common revitalization mechanism is to apply it to land in the same water shed. However, such operations have become an environmental concern for a number of reasons, and in view of the large volume of manure produced (e.g. estimated to be about 1.4 billion tons of manure in the U.S.A. Alone in 1998), stockpiles of manure and other waste products are becoming a significant cause for concern.
While presently a cause for concern, raw manure, when properly processed, has many applications. It can be used as a fertilizer, a soil amendment for such areas as parks, golf courses, and lawns, and in a number of other situations. In known systems, raw manure is typically mechanically milled or ground with hammer mills or grinders prior to processes in which the manure is dried in a rotary drum drier at between 350-500° F. using an external heat source. A roll compact or is then used to form brunettes from the pulverized and dried raw manure, which are then re-ground to a desired granule size. Such systems have a number of environmental and economic drawbacks that make them largely, or wholly, not cost effective.
Not only is conventional processing marginally or not cost effective, it also significantly reduces the quality of the processed product. The heat used for drying not only is produced expensively and with environmental adverse consequences, but it destroys a significant amount of the organic material in the manure. Also, the forming process produces a greater volume of airborne products that can present a health and safety hazard, requiring the utilization of air pollution controls.